Receive the latest national-international updates in your inbox

Prosecutors upgrated the charges to third-degree murder for the backhoe operator allegedly involved in the Center City building collapse. NBC10's Daralene Jones has the details. (Published Wednesday, Feb 19, 2014)

Updated at 12:08 AM PDT on Wednesday, Feb 19, 2014

The backhoe operator implicated in last summer's deadly building collapse in Philadelphia is facing upgraded charges.

Sean Benschop, a.k.a. Kary Roberts, had six counts of involuntary manslaughter upgraded to charges of third degree murder during a preliminary hearing in the Court of Common Pleas on Tuesday. The man has pled not guilty to the charges.

Benschop, 43, was operating the excavator at the site of a building demolition at 2136 Market Street on the morning of June 5, 2013 when the building's western wall collapsed. The four-story brick wall was free-standing and had not been braced using demolition equipment.

The debris from the wall crushed the one-story Salvation Army Thrift Shop next door, on the corner of 22nd and Market Streets, burying shoppers and store clerks alive. Six people died in the collapse, and 13 others were injured.

Benschop was arrested shortly after the collapse and underwent drug and alcohol tests. Police said those tests came up positive for prescription painkiller and marijuana use. The man, however, did have a broken arm, for which he said the painkillers were being used.

He and his family have maintained the man's innocence during the entire ordeal. His attorney, Daine Grey, told NBC10 Philadelphia in September 2013 that he believed evidence would vindicate his client.

Along with the newly upgraded charges, Benschop also still faces 13 counts of reckless endangerment. Should he be found not guilty of the murder charges he could still be found guilty of involuntary manslaughter.

Benschop was the only man charged in the case for several months, until Griffin T. Campbell, the contractor on the job, was arrested last November.

Campbell, 49, stands charged with six counts of third degree murder, six counts of involuntary manslaughter and 13 counts of recklessly endangering another person.

Philadelphia District Attorney Seth Williams said the building was not properly demolished and that those involved ignored safety advice.

He also said additional charges could be brought forward at a later time based on the investigation.

Plato Marinakos, the architect and the expeditor for the construction project at the building, also spoke in court on Tuesday and provided prosecutors with pictures he took with his camera a day before the collapse.

Marinakos, a key witness for prosecutors in their case against Benschop and Campbell, was granted immunity in exchange for his testimony.

“This whole construction site became extraordinarily dangerous very quickly,” said Assistant District Attorney Jennifer Selber. “Plato Marinakos himself didn’t get there until 6 p.m. on the Tuesday evening before the collapse. When he saw the inherent danger, he immediately told Griffin Campbell, who knew anyway.”

Jay Bryan, the father of Anne Bryan, who was killed in the collapse, told NBC10 he hoped the ongoing grand jury investigation would lead to more results.

"We're grateful that it sounds like the investigation is ongoing," Bryan said. "We hope that everyone will be held accountable from bottom to top."